Preparing aluminous abrasives.



l'l as T0 NORTON COMP i I SSACEUSETEh.

aeeae. E0 Drawing. I

To all whom it may concern Be it known that we, Lnwrs E. Seem) and RAY HILL WHITE, citizens of the Uni ti States, residing at Niagara Falls, in the county of Niagara and State of New York,

have invented certain new and useful Improvements in Preparing Alumin'ous; Ab-

rasives, of which the following is a specification.- I I a It is known that an appreciable reduction of alumina is apt to occur when calcined bauxlte or other alumlnous raw material is minum) are highly objectionable constitucuts of the product, tending to its disintegration in presence of moisture. The tendency to the formation of these reduction products is more pronounced as the alumina is of higher purity, inasmuch as the oxids' of iron and silicon are more easily re= ducible than alumina, andthereby serve to prevent reduction of alumina so long as they are present in the charge in substantial, excess of the carbon available for the reduc-.

tion. We have found that the formation of 4 these reduction products of alumina may be prevented by incorporatingwith the aluminous material to be fused an ap ropriate amount of an oxidizing addition wh ch yields volatile reaction products. This presents the important advantage, as compared with a similar use of iron oxid or thelike, that the reaction products do not remaln in or associated with the fused alumina, but are driven ofi", for the most part at least, during .the-furnacing operation. 4

As such oxidizing additions, we may use oxygen-compounds oi sodium or zinc, as for example soda-ash, anhydrous sodium sulfate,

zinc oxid or the like. The quantity to'be used is of course dependent upon the amount of carbon present, or 'upon' the carbon su'r i'aces presented to the charge, Under usual operating conditions, however, from one to five per cent of such addltions will sufice to 1 "=2 1: r nine-ans rains, new ran or woncns'raniranssacnusarrs, a. conroaa'rron or inn; bodies as the oxide method of a which consists in adding tothe charge to be f i li .t. t Ki lbeautification of Letters ratent. wnthpmppafl gam 1% was, a lication can august is, new. sex-nu no. acacia.

prevent the occurrence in the l product of the objectionable reduction products of alumina, while at the same time the oxidia= mg addltlons themselves disappear in the course of the turnacing operation, either wholly or to such extent as to leave no residual imglurities of objectionable naturein the sod product.

Nevertheless, other eects due to the use of these oxidizing additions are at time'e-ob served. For example, in the case of sodium compounds there is a marked weakening of the abrasive-grain, whether the addition is made to substantially pure alumina as disclosed No. 184,110, filed Aug. 2', 1917, or to ordibauxite as disclosed in our copending app 1cat1on Serial No. 184=,111, filed dug.

in our copending application Serial till till

'2, 1917... According to the present invention,

however, the primary purposeof the oxidizinp; addition is to avoid reduction of alumina, whether supplied in a state of substantial purity or in the form of bauxite, by the action of the-carbon electrodes or furnace hearth or of carbon mixed with the charge for the purpose of reducingv the impurities present: and for this purpose, any oxidizing addition whereof the reduction products are volatile at the operating temptures is regarded as equivalent to the oxygen compounds ofsodium.

.llhe' proportion of the oxidizing addition will of course vary considerably in accordshoe with the amount of carbon in the. Y

- charge or exposed to the'charge, a due allowance being made in the case of such imtherein as normal impurities of such oxidistitanium.

*We claim:--

- l. In the art of preparing aluminous abrasives by theelectricufurnace fusion of alummous materlalsin presence of carbon, the preventing reduction of alumina,

fused a relatively small proportioned an oxygen-containing substance of which the reduction products furnacingcondition c 2. lnthe art of wagering aloue abrasives'by. the electric rnace fusion ct aluminouis materials inipresence at carbon, the method of pventingg reduction of rd of iron, silicon and are volatile under the not till pure materials as bauxite. for the presence fused a, relatively small proportion of 2m oxygen-compound of avolatile metal.

3. In the m of preparing aluminous mb- 5 msivga by Hm @lectric furnace) fusien of alummous' mammals in presance of carbon, the methczdl' of preventmg reductiun of will miim which consisizs in adding t6 the charga Kn irestlmony whemf, We mfix our signa- LEWIS 5E, mmmms; mm mm WHITE. 

